I notice there is no export in the code of Movilizer.js. So, it is not a module. Then, you can't import it.

You could load it in the browser, not as a module but as a script (for example, not in Webpack, but with a markup <script>). Then it will exist as a global variable. In TypeScript, we can expect that the file Movilizer/index.d.ts declares the global variable. Therefore, you can just use it.